In disposing a rigid board over a bending portion of a steel case of an electronic instrument, generally, the rigid board is divided into a plurality of pieces which are to be connected with one another by utilizing a flexible board.
Such a rigid-flexible board can be made as a printed circuit board as follows. In this case, a plurality of rigid-flexible board can be obtained from the printed circuit board.
(1) A rigid board is formed so as to comprise a plurality of unit flexible boards, a plurality of circuit patterns, each being provided on the corresponding unit flexible board, and a plurality of circuit patterns, each being provided at the corresponding unit rigid board as an inner plate.
(2) A rigid board is formed so as to compose a cupper layer on the top surface or the bottom surface thereof which is to be contacted to the flexible board so that the rigid board is laminated with the flexible board. The portion of the rigid board corresponding to the unit flexible board is punched out.
(3) The rigid board formed in the step (1) is laminated on the flexible board formed in the step (2) at the main surface of the flexible board under the condition that a releasing film and a cover film are formed at the punched out portion of the rigid board. Then, the rigid board and the flexible board are combined with one another through thermal pressing.
(4) The rigid board is laminated on the flexible board at the backside of the flexible board under the condition that a releasing film and a cover film are formed at the punched out portion of the rigid board. Then, the rigid board and the flexible board are combined with one another through thermal pressing.
(5) Then, the releasing film and the cover film are removed so that the laminated body is divided into unit sheets for package.
(6) After the packaging step, rigid-flexible boards are divided individually from the unit sheets.
In the present specification, the wording “unit board” means a minimum unit board under manufacture, and the wording “complex board” means a single board made by combining a different kinds of unit boards. In the present specification, the wording “unit sheet for package” means a unit for package which is composed of a plurality of unit boards or a plurality of complex boards. In the present specification, the wording “assembled panel” means a board to be functioned as a single board wherein a plurality of boards are built in one board or a plurality of complex boards are built in one board, and then, to be divided into unit boards, complex unit boards or unit sheets for package after manufacturing process. In the present specification, the wording “horizontal circuit area” means an interlayer circuit of an circuit board, and the wording “vertical circuit area” means an interlayer connection for connecting different circuit layers at a single board or a complex board, and the wording “connector” means a connector for electrically connecting boards. As the connector, a conductive bump, a pad, a portion of the horizontal circuit area can be exemplified.
In a conventional manufacturing method of printed circuit board assembled panel, however, the intended assembled panel can be made by using a flexible board with the same size as the assembled panel so that the productive cost of the assembled panel can be increased because the flexible board is expensive.
In the conventional manufacturing method, it is required that a frame for handling is formed at each printed circuit board by cutting off the corresponding portion of the printed circuit board so that much waste is created and thus, the material using efficiency is deteriorated.
Moreover, in the conventional assembled panel, since the finally shaped printed circuit boards are built in a large board, if one unit sheet is failed, the assembled panel is also failed so that the productive yield of the assembled panel is lowered.